Safety knife

ABSTRACT

The safety knife of this invention includes a cutting blade, at least one guard, and a handle. The cutting blade has a cutting edge adapted to perform a cutting function and is a substantially flat, elongated member. The guard is disposed substantially parallel to the cutting blade with a space between at least a portion of the cutting blade and at least a portion of the guard. The guard is a flat elongated member adapted to prevent the cutting edge of the cutting blade from injuring the user of the safety knife. A handle is disposed at one end of the cutting blade and guard. The handle is adapted to be gripped by the user of the safety knife. Preferably, the safety knife includes two guards, one guard disposed on each side of the cutting blade, substantially parallel to the cutting blade. The safety knife has a space between at least a portion of each guard and at least a portion of the cutting blade. One example of a use for the safety knife is for performing cutting functions on a belt webbing, such as a belt webbing adapted for use in safety belts for vehicles.

[ Nov. 11, 1975 SAFETY KNIFE Raymond Theodore Hyba, Mt. Clemens, Mich.

[75] Inventor:

[73] Assignee: Allied Chemical Corporation, New

York, NY.

[22] Filed: July 2, 1974 [21] Appl. No.: 485,197

[52] US. Cl 30/287; 30/289 [51] Int. Cl. B26B 11/00 [58] Field of Search 30/286, 287, 289, 288,

30/293, 304, DIG. 8, 294, 136; 7/l4.l

[56] References Cited UNITED STATES PATENTS 612,945 10/1898 I-lockerson 30/286 1,399,924 12/1921 Berthelsen 30/289 2,360,652 10/1944 Cummings 30/286 2,764,814 10/1956 Jecker 30/294 FOREIGN PATENTS OR APPLICATIONS 75,110 5/1894 Germany 30/289 Primary E.\'aminer.1ames L. Jones, Jr. Assistant ExaminerJ. C. Peters Attorney, Agent, or Firm-John P. Kirby, Jr.

157] ABSTRACT The safety knife of this invention includes a cutting blade, at least one guard, and a handle. The cutting blade has a cutting edge adapted to perform a cutting function and is a substantially flat, elongated member. The guard is disposed substantially parallel to the cutting blade with a space between at least a portion of the cutting blade and at least a portion of the guard. The guard is a flat elongated member adapted to prevent the cutting edge of the cutting blade from injuring the user of the safety knife. A handle is disposed at one end of the cutting blade and guard. The handle is adapted to be gripped by the user of the safety knife. Preferably, the safety knife includes two guards, one guard disposed on each side of the cutting blade, substantially parallel to the cutting blade. The safety knife has a space between at least a portion of each guard and at least a portion of the cutting blade. One example of a use for the safety knife is for performing cutting functions on a belt webbing, such as a belt webbing adapted for use in safety belts for vehicles.

8 Claims, 18 Drawing Figures U.S. Patent Nov. 11, 1975 Sheetlof3 3,918,157

Sheet 3 of 3 SAFETY KNIFE BACKGROUND OF THE INVENTION This invention relates to a safety knife adapted to prevent a cutting edge of a blade of the knife from injuring the user of the knife. One example of a use for the safety knife is for performing cutting functions on a belt webbing, such as a belt webbing adapted for use in safety belts for vehicles.

SUMMARY OF THE INVENTION The safety knife of this invention includes a cutting blade, at least one guard, and a handle. The cutting blade has a cutting edge adapted to perform a cutting function. The guard is disposed substantially parallel to the cutting blade with a space between at least a portion of the cutting blade and at least a portion of the guard. The guard is a flat elongated member adapted to prevent the cutting edge of the cutting blade from injuring the user of the safety knife. A handle is disposed at one end of the cutting blade and guard. The handle is adapted to be gripped by the user of the safety knife.

Preferably the safety knife includes two guards, one guard disposed on each side of the cutting blade, sub stantially parallel to the cutting blade. The safety knife has a space between at least a portion of each guard and at least a portion of the cutting blade. The guards each have a leading edge disposed substantially parallel to the cutting edge of the cutting blade. The cutting edge of the cutting blade is recessed with reference to the leading edge of the guards to protect the user from injury by the cutting edge of the cutting blade.

The cutting blade has a tip and each guard has a tip. The tip of the cutting blade is recessed with reference to the tips of the guards to protect the user from injury by the tip of the cutting blade. The blade and the guards each have a trailing edge. Optionally, the guards each have an inset portion at the trailing edge. The trailing edges of the guards at the inset portion are recessed with reference to the trailing edge of the blade. The cutting blade has a handle portion at the opposite end of the cutting blade from the cutting blade tip. Each guard has a handle portion at the opposite end of the guard from the guard tip. The cutting blade handle portion and the guard handle portions are joined together to form the handle of the safety knife.

The guards each further include a guard portion ex tending along part of the length of the guard from the guard tip and a shoulder between the handle portion and the guard portion of the guard. The shoulders are arranged adjacent to one another and to the cutting blade. The thickness of the handle portion of the guard is larger than the thickness at the guard portion of the guard. The difference in thickness results in the space between the guards and the blade.

Optionally, the safety knife further includes a rounded portion at the tip of the cutting blade to protect the user from injury by the tip of the cutting blade.

DESCRIPTION OF THE DRAWINGS FIG. I is a side elevational view of the safety knife of this invention, showing a cutting blade and two guards.

FIG. 2 is a top view of FIG. 1.

FIG. 3 is an end view of FIG. 1 in the direction of arrow A in FIG. 1.

FIG. 4 is a side elevational view of a portion of FIG. 1, showing one guard.

FIG. 5 is a top view of FIG. 4.

FIG. 6 is an end view of FIG. 4 in the direction of arrow B in FIG. 4.

FIG. 7 is a cross-sectional view of FIG. 4 along the lines 77 in FIG. 4.

FIG. 8 is a cross-sectional view of FIG. 4 along the lines 8-8 in FIG. 4.

FIG. 9 is a cross-sectional view of FIG. 4 along the lines 99 in FIG. 4.

FIG. 10 is a bottom view of a portion of FIG. 4 in the direction indicated by arrow C in FIG. 4.

FIG. 11 is a side elevational view of a portion of FIG. 1 showing the cutting blade without a rounded portion at the tip of the blade.

FIG. 12 is a cross-sectional view of FIG. 11 along the lines l2I2.

FIG. 13 is a cross-sectional view of FIG. 1 1 along the lines 1313.

FIG. 14 is a side elevational view of a portion of FIG. 1, showing the cutting blade with a rounded portion at the tip of the blade.

FIG. 15 is an end view of FIG. 14 in the direction of arrow 15 in FIG. 14.

FIG. 16 is a side elevational view of the second guard shown in FIG. 1.

FIG. 17 is a top view of FIG. 16.

FIG. 18 is an example of a use for the safety knife of FIG. 3 to open the seams of a safety belt webbing.

DETAILED DESCRIPTION Referring to FIGS. 1 and 2, the safety knife of this invention, referred to generally by the numeral 2, includes a cutting blade 4, at least one guard 6, and a handle, referred to generally by the numeral 8. Referring to FIGS. 1, 3 and 11-15, the cutting blade 4 has a sharp cutting edge 10 adapted to perform a cutting function. The cutting blade 4 is an elongated member having a substantially flat plane. Referring to FIGS. 2 and 3, the guard 6 is disposed substantially parallel to the cutting blade 4 with a space 12 between at least a portion of the guard 6 and at least a portion of the cutting blade 4. The guard 6 is an elongated member having a substantially flat plane. The guard 6 is adapted to prevent the cutting edge 10 (FIGS. 2 and 3) of the blade 4 from injuring the user of the safety knife 2. Preferably, the safety knife 2 has two guards 6, one guard 6 shown in FIGS. 4 and 5 and the second guard 6 shown in FIGS. 16 and 17. One guard 6 is disposed on each side of the cutting blade 4. The flat plane of each guard 6 is disposed substantially parallel to the flat plane of the cutting blade 4. Preferably, the safety knife 2 has two spaces 12, one space 12 between at least a portion of each guard 6 and at least a portion of the blade 4. Referring to FIGS. 1 and 2, the handle 8 is disposed at one end of the cutting blade 4 and guard 6. The handle 8 is adapted to be gripped by the user of the safety knife 2.

Referring to FIGS. 1, 2, 4, 5, 16 and 17, the guards 6 each have a leading edge 14 disposed substantially parallel to the cutting edge 10 (FIGS. 1, 11, 12, 14 and 15) of the cutting blade 4. The cutting edge 10 of the cutting blade 4 is recessed with reference to the leading edge 14 of the guards 6 to protect the user from injury by the cutting edge 10 of the cutting blade 4. The cutting blade 4 has a tip 16. Each guard 6 has a tip 18. The

tip 16 of the Cutting blade 4 is recessed with reference to the tips 18 of the guards 6 and the areas of the guards adjacent to the tips 18 of the guard 6 to protect the user from injury by the tip 16 of the cutting blade 4.

Referring to FIG. 18, one example of a use for the safety knife 2 of this invention is in the manufacture or assembly of vehicle safety belts. Typically, the fabric of the safety belt webbing is sewn together at selected joints. Occasionally, it is desirable to open the seams of a safety belt web previously sewn together. Referring to FIG. 18, a portion of each of the loose ends 30 of the safety belt webbing, referred to generally by the numeral 32, is each placed in one of the two spaces 12 between the cutting blade 4 and a guard 6. When the safety knife 2 is moved toward the portion 34 of the belt webbing 32 which has been sewn together, the cutting edge of the cutting blade 4 cuts through the threads joining the sewn portion 34 of the belt webbing 32. One important advantage of the safety knife 2 is that the user of the safety knife 2 can perform this cutting function and be protectedfrom injury by the cuttingedge 10 of the cutting blade 4 and the tip 16 of the cutting blade 4. Another important advantage of the safety knife 2 is that it can separate such a sewn portion 34 or a seam or plurality of seams quickly and efficiently, usually with one cutting stroke. Thus, the safety knife 2 reduces injuries and increases efficiency. The safety knife 2 is adapted to perform many other cutting functions.

Referring to FlGS. 1, l1 and 14, the cutting blade 4 has a trailing edge 20. Referring to FIGS. 1, 4 and 16, the guards 6 each have a trailing edge 22. Optionally, the guards 6 each have an inset, cut-out portion 24, at their trailing edges 22. Optionally, the trailing edges 22, of the guards 6 at their inset portions 24 are recessed with reference to the trailing edge 20 of the cutting blade 4. The inset portions 24 of the trailing edges 22 of the guards 6 allow a portion of the trailing edge 20 of the cutting blade 4 to extend above the recessed portion of the trailing edges 22 of the guard 6. The trailing edge 20 of the cutting blade 4 is blunt, rather than having a sharp cutting edge. Thus, the trailing edge 20 of the cutting blade 4 does not present a safety hazard to the user because it is blunt enough not to cut the user. However, the portion of the trailing edge 20 of the cutting blade 4 which extends above the trailing edges 22 of the guards presents a useful scraping surface adapted to scrape loose thread or other matter from a safety belt webbing after the cutting operation has been performed. Preferably, the length of the inset portion 24 is 10 to 50% greater than the width of a safety belt. Referring to FIG. 3, each guard 6 has a bevelled edge 23 on the inside of its trailing edge 20 to facilitate this scraping function.

Referring to FIGS. 2, 11 and 14, the cutting blade 4 has a handle portion at the opposite end of the cutting blade 4 from the tip 16. Referring to FIGS. 1, 2, 4, 5, 16 and 17, the guards 6 each have a handle portion 42 at the opposite end of the guards 6 from the guard tip 18. The cutting blade handle portion 40 and the guard handle portions 42 are joined together to form the handle 8 of the safety knife 2. Preferably, the means to join the cutting blade handle portion 40 and the guard handle portions 42 together is removable, such as screw 44. Such a removable means allows the cutting blade 4 and guards 6 to be taken apart conveniently to sharpen the cutting blade 4.

Still more preferably, two separate means may be used to join the cutting blade handle portion 40 and the t ting blade 4 need not be separated completely from one another, with the possibility of being misplaced, but the cutting blade 4 is merely swivelled on remote means 46, such as a screw or rivet, to sharpen the blade.

Referring to FIGS. 2, 5 and 17, the guards 6 each have a guard portion 48 adjacent to the guard tips 18. The handle portions 42 of the guards 6 extend from the ends 49 of the guards 6 remote from the guard tip 18 along approximately 30 to 60% of the length of the guards 6. Preferably, the handle portions 42 extend from ends 49 along approximately 40% of the length of the guard 6. The guard portions 48 of the guards 6 extend from the guard tips 18 along approximately 40 .to and preferably 60% of the length of the guard6. The thickness of the guards 6 at the handle portions 42 is larger than the thickness at the guard portions 48 of i the guard 6. Preferably the thickness at the handle por tions 42 is approximately 20 to 60% of the thickness at the guard portions 48. The guards 6 each have a shoulder 50 in the middle portion of the guards 6 between the handle portions 42 and the guard portions 48. Referring to FIG. 2, when the guards 6 are joined with the cutting blade 4, the shoulders 50 are arranged adjacent: I

to one another and to the cutting blade 4. Asa result of the differences in thickness between the handle portions 42 and the guard portions 48, spaces 12 are provided between each guard portion 48 and the cutting blade 4. The spaces 12 extend from the tips of the cutting blade to the shoulder 50 of the guards 6. The

a cutting blade having a cutting edge to perform a 1 cutting function;

two guards, one guard disposed on each side of said cutting blade, substantially parallel to sajd cutting blade, said knife having a space between at least a portion of each guard and at least a portion of said blade, said guards being flat elongated members to prevent said cutting edge of said blade from injuring the user of the safety knife;

a handle disposed at one end of said cutting blade and guard, said handle being adapted to be gripped by the user of said safety knife; and

said blade and said guards each having a trailing edge, said guards having an inset portion at said edge of said cutting blade extending above the re-:

cessed portion of said trailing edge of said guards to provide a useful scraping surface.

2. The safety knife according to claim 1 wherein said guards each have a leading edge disposed substantially parallel to said cutting edge of said cutting blade, said cutting edge of said blade being recessed with reference to said leading edge of said guards to protect the user from injury by said cutting edge of said blade.

3. The safety knife according to claim 1 wherein said cutting blade has a tip and each said guard has a tip,

-said tip of said cutting blade being recessed with reference to said tips of said guards to protect the user from injury by said tip of said cutting blade.

4. The safety knife according to claim 3 wherein said cutting blade has a handle portion at the opposite end of said cutting blade from said cutting blade tip; and each said guard has a handle portion at the opposite end of said guard from said guard tip, said cutting blade handle portion and said guard handle portions being joined together to form said handle of the said safety knife.

5. The safety knife according to claim 3 and further comprising a rounded portion at the tip of said cutting blade to protect the user from injury by said tip of said blade.

6. The safety knife according to claim 4 wherein said guards each further comprise:

a guard portion extending along part of the length of said guard from said guard tip; and

a shoulder between said handle portion and guard portion of said guard, said shoulders arranged adjacent to one another and to said cutting blade.

7. The safety knife according to claim 6 wherein the thickness at the handle portion of said guards is larger than the thickness at the guard portion of said guards, said difference in thickness resulting in said space between said guards and said blade.

8. A safety knife comprising:

a cutting blade having a cutting edge to perform a cutting function, said cutting blade having a tip and a handle portion at the opposite end of said cutting blade from said cutting blade tip;

two guards, one guard disposed on each side of said being recessed with reference to said leading edge of said guards to protect the user from injury by said cutting edge of said blade;

each said guard having a tip, said tip of said cutting blade being recessed with reference to said tips of said guards to protect the user from injury by said tip of said cutting blade, each guard having a handle portion at the opposite end of said guard from said guard tip, said cutting blade handle portion and said guard handle portions being joined together to form a handle for said safety knife, said handle being adapted to be gripped by the user of said safety knife; each guard having a guard portion extending along part of the length of said guard from said tip and a shoulder between said handle portion and said guard portion of said guard, said shoulders arranged adjacent to one another and to said cutting blade, the thickness of the handle portion of said guards being larger than the thickness at the guard portion of said guards, said difference in thicknesses resulting in a space between a portion of said cutting blade and a portion of each guard;

said blade and said guards each have a trailing edge,

said guards each having an inset portion at said guard trailing edges, said trailing edges of said guards at the inset portion being recessed with reference to said trailing edge of said blade, a portion of said trailing edge of said cutting blade extending above the recessed portion of said trailing edges of said guards to provide a useful scraping surface.

l l I 

1. A safety knife comprising: a cutting blade having a cutting edge to perform a cutting function; two guards, one guard disposed on each side of said cutting blade, substantially parallel to said cutting blade, said knife having a space between at least a portion of each guard and at least a portion of said blade, said guards being flat elongated members to prevent said cutting edge of said blade from injuring the user of the safety knife; a handle disposed at one end of said cutting blade and guard, said handle being adapted to be gripped by the user of said safety knife; and said blade and said guards each having a trailing edge, said guards having an inset portion at said guard trailing edge, said guard trailing edge at said inset portion being recessed with reference to said trailing edge of said blade, a portion of said trailing edge of said cutting blade extending above the recessed portion of said trailing edge of said guards to provide a useful scraping surface.
 2. The safety knife according to claim 1 wherein said guards each have a leading edge disposed substantially parallel to said cutting edge of said cutting blade, said cutting edge of said blade being recessed with reference to said leading edge of said guards to protect the user from injury by said cutting edge of said blade.
 3. The safety knife according to claim 1 wherein said cutting blade has a tip and each said guard has a tip, said tip of said cutting blade being recessed with reference to said tips of said guards to protect the user from injury by said tip of said cutting blade.
 4. The safety knife according to claim 3 wherein said cutting blade has a handle portion at the opposite end of said cutting blade from said cutting blade tip; and each Said guard has a handle portion at the opposite end of said guard from said guard tip, said cutting blade handle portion and said guard handle portions being joined together to form said handle of the said safety knife.
 5. The safety knife according to claim 3 and further comprising a rounded portion at the tip of said cutting blade to protect the user from injury by said tip of said blade.
 6. The safety knife according to claim 4 wherein said guards each further comprise: a guard portion extending along part of the length of said guard from said guard tip; and a shoulder between said handle portion and guard portion of said guard, said shoulders arranged adjacent to one another and to said cutting blade.
 7. The safety knife according to claim 6 wherein the thickness at the handle portion of said guards is larger than the thickness at the guard portion of said guards, said difference in thickness resulting in said space between said guards and said blade.
 8. A safety knife comprising: a cutting blade having a cutting edge to perform a cutting function, said cutting blade having a tip and a handle portion at the opposite end of said cutting blade from said cutting blade tip; two guards, one guard disposed on each side of said cutting blade substantially parallel to said cutting blade, said guards each having a leading edge disposed substantially parallel to said cutting edge of said cutting blade, said cutting edge of said blade being recessed with reference to said leading edge of said guards to protect the user from injury by said cutting edge of said blade; each said guard having a tip, said tip of said cutting blade being recessed with reference to said tips of said guards to protect the user from injury by said tip of said cutting blade, each guard having a handle portion at the opposite end of said guard from said guard tip, said cutting blade handle portion and said guard handle portions being joined together to form a handle for said safety knife, said handle being adapted to be gripped by the user of said safety knife; each guard having a guard portion extending along part of the length of said guard from said tip and a shoulder between said handle portion and said guard portion of said guard, said shoulders arranged adjacent to one another and to said cutting blade, the thickness of the handle portion of said guards being larger than the thickness at the guard portion of said guards, said difference in thicknesses resulting in a space between a portion of said cutting blade and a portion of each guard; said blade and said guards each have a trailing edge, said guards each having an inset portion at said guard trailing edges, said trailing edges of said guards at the inset portion being recessed with reference to said trailing edge of said blade, a portion of said trailing edge of said cutting blade extending above the recessed portion of said trailing edges of said guards to provide a useful scraping surface. 